<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core_rt" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>测试if</h1>
<form action="tag.jsp" method="get">
    <input type="text" name="username" value="${param.username}">
    <input type="submit" value="点我判断">
</form>

<%--判断username是否admin--%>
<c:if test=""></c:if>
<c:if test="${param.username=='admin'}" var="isAdmin">
    <c:out value="管理员欢迎您！！！"></c:out>
</c:if>

<c:out value="${isAdmin}"></c:out>
</body>
</html>
